Reduction type polycarboxylic acid water reducer as well as preparation method and application thereof

Abstract

The invention relates to a reduction type polycarboxylic acid water reducer as well as a preparation method and application thereof. The water reducer is prepared from the following raw materials: an unsaturated polyether macromonomer, an unsaturated acid monomer and a reduction type functional monomer, and further comprises an initiator, a chain transfer agent and deionized water, wherein the molar ratio of the unsaturated polyether macromonomer to the unsaturated acid monomer to the reduction type functional monomer is 1: (4-6): (2-5). Isopentenyl polyoxyethylene ether, the unsaturated acid monomer, the reduction type functional monomer, the chain transfer agent, the initiator and the deionized water are adopted, and the polycarboxylic acid water reducer with high water-reducing rate and excellent shrinkage-reducing performance is prepared by a free radical copolymerization method through molecular structure design. The water reducer is used for reducing the shrinkage rate of a cementing material, and the mixing amount of the water reducer in the cementing material is 0.1-0.2% of the mass of the cementing material. Compared with the prior art, the reduction type polycarboxylic acid water reducer has the advantages of low doping amount, excellent reduction effect, simple synthesis process, energy saving, environmental protection and the like.

Description

technical field [0001] The invention relates to the field of concrete admixtures, in particular to a shrinkage-reducing polycarboxylate water reducer and its preparation method and application. Background technique [0002] The cracking caused by the volume shrinkage of concrete seriously affects the safety, durability and aesthetics of concrete structures. From bridges, roads and other transportation facilities to coastal seaport engineering structures, from civil buildings, commercial buildings to industrial buildings, the impact of cracking problems is very extensive. Therefore, reducing the volume shrinkage of concrete and controlling the internal defects of concrete are very important to improve the application performance of concrete. [0003] At present, in order to deal with the shrinkage of concrete in engineering, in addition to taking measures such as adding structural steel bars, setting construction joints, reducing the temperature difference between the inside...

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Problems solved by technology

[0003] At present, in order to deal with the shrinkage of concrete in engineering, in addition to taking measures such as adding structural steel bars, setting construction joints, reducing the temperature difference between the inside and outside of concrete, strengthening wet curing and other structural design and adjusting the curing system, the main method is to add expansion agents, fibers or shrinkage reducing agents. and other methods to solve the adverse effects of concrete shrinkage. These measures have a certain effect on controlling the volume shrinkage of concrete, but they also have certain limitations.

For example: the amount of expansion agent is usually large and difficult to control, and the requirements for concrete curing conditions are relatively strict; the addition of fibers can play a role in dispersing the shrinkage stress distribution of concrete, but it cannot fundamentally reduce the shrinkage of concrete, and the fiber The price is high, and the compatibility with concrete needs to be further improved; although the shrinkage reducer can effectively inhibit the shrinkage of concrete, it also has a large dosage (the dosage is usually polycarboxylate water reducer about ten times of that), the price is high, and the shrinkage reducing agent needs to be used in combination with other admixtures such as water reducing agents. There is a problem of adaptability between the shrinkage reducing agent and other admixtures. When it is too high, it will also have an adverse effect on the strength of concrete.

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